1. Field of the Invention
The present invention relates to emulsified beverages which have been filled in airtight storage packages such as PET bottles, cans, drink boxes, paper packages or airtight plastic cups; and which exhibit excellent emulsion stability over a long period of time and maintain good taste even if sold under heating in a vending machine or at storefront, at ordinary temperatures, or under cooling.
2. Discussion of the Background
Emulsified beverages such as milk coffee, milk tea and cocoa usually contain animal fat originated from milk. In recent days, there has been an attempt to replace the animal fat in such drinks with a vegetable fat with a view toward lowering the blood cholesterol level (Japanese Patent Laid-Open Nos. 222553/1992 and 159753/1980).
On the other hand, diglyceride-containing beverages are reported because they are physiologically effective for lowering the neutral fat level in the blood and suppressing body fat accumulation (Japanese Patent Laid-Open Nos. 23941/1996 and 104917/1988).
For effective exhibition of such physiological effects of diglycerides, an increase in their content is desired and intake of them in the beverage form is preferred from the viewpoints of palatability and easy intake.
Incorporation of a large amount of diglycerides in coffee, tea or the like beverage is however accompanied with such a problem that the taste which is the sole merit of such a beverage is impaired rightly after preparation. In particular, sterilization, for example, by heating is indispensable for preparation of a packaged beverage but it causes a marked deterioration in taste. Incorporation of diglycerides in a beverage causes unsatisfactory emulsification or dispersion, though depending on their amount, and tends to deteriorate the appearance or taste of the beverage with the passage of time, for example, a creaming or separating phenomenon between oil phase and aqueous phase occurs during storage or an increase in the size of the emulsified and dispersed particles or precipitation of a solid occurs. Such a change in taste or appearance has posed a severe problem for sales of a packaged diglyceride-containing beverage on the market.
An object of the present invention is therefore to provide a packaged emulsified beverage which contains a large amount of diglycerides, and in spite of a high content, has good taste rightly after preparation even if it has been sterilized and exhibits stable appearance and taste even after long storage.
The present inventors have therefore prepared packaged emulsified beverages by adding various components to diglycerides and investigated their taste and stability. As a result, it has been found that a packaged emulsified beverage containing, in combination, a diglyceride having a specific fatty acid constitution and a phospholipid or lipoprotein has good taste even after sterilization by heating and exhibits stable appearance and taste even after storage over long hours.
In the present invention, there is thus provided a packaged emulsified beverage comprising the following components (A) and (B):
(A): a diglyceride, having in the fatty acid constituents thereof, 15 to 90 wt. % of an xcfx89-3 unsaturated fatty acid; and
(B) a lipid selected from the group consisting of phospholipids, lipoproteins and a mixture thereof.
The packaged emulsified beverage according to the present invention has good taste even after sterilization and is excellent in long shelf life.
Within the context of the present invention, the term xe2x80x9cpackaged emulsified beveragexe2x80x9d as used herein means an emulsified beverage hermetically sealed in a beverage package without dilution.
The diglyceride serving as Component (A) in the present invention contains, in the fatty acid constituents thereof, an xcfx893 unsaturated fatty acid in an amount of 1.5 to 90 wt. %, preferably 40 to 75 wt. %, especially 40 to 60 wt. %. Within the above-described ranges, the resulting beverage can exhibit excellent physiological effects which the diglyceride originally has such as neural lipid lowering effects and body fat accumulation resisting effects, and at the same time has emulsion stability and good taste.
The term xe2x80x9cxcfx893 unsaturated fatty acid xe2x80x9d as used herein means an unsaturated fatty acid having, at the third carbon atom from the xcfx89 position thereof, a first unsaturated bond and having at least two unsaturated bonds. Of such xcfx893 unsaturated fatty acids, those having 12 to 24 carbon atoms are preferred, with xcex1-linolenic acid, docosahexaenoic acid and eicosapentaenoic acid being more preferred. As the xcfx893 unsaturated fatty acid, xcex1-linolenic acid is especially preferred. Although the diglyceride separated and purified from an oil/fat may be added, an oil/fat containing the diglyceride is usually added to the beverage.
The above-described oil/fat containing the diglyceride serving as Component (A) is available by conventional methods known to those of ordinary skill in the art without undue experimentation, such as by any one of hydrolysis reaction of a linseed coil, perilla oil, soybean oil or rapeseed oil containing an xcfx893-unsaturated acyl group, ester exchange reaction of the above-exemplified oil/fat with glycerin, or esterification of a fatty acid derived from such an oil/fat with glycerin. The reacting method may be either one of chemical reaction in the presence of an alkali catalyst or biochemical reaction using an enzyme, which may be immobilized, such as lipase. The resulting oil/fat composition containing the diglyceride may be added with a vegetable oil such as soybean oil, rapeseed oil, palm oil, rice oil or corn oil, or an animal oil such as beef tallow or fish oil; or hydrogenated, fractionated or random ester exchange oil thereof to adjust the content of the diglyceride, monoglyceride, triglyceride and/or free fatty acid in the composition.
It is preferred that from the viewpoint of emulsion stability, the unsaturated fatty acids amount to at least 50 wt. %, more preferably at least 60 wt. %, especially at least 70 wt. % of all the fatty acid constituents of Component (A). The term xe2x80x9cunsaturated fatty acidsxe2x80x9d as used herein embraces not only xcfx893 but also xcfx899 and xcfx896 ones. The unsaturated fatty acids have preferably 12 to 24 carbon atoms, especially 12 to 22 carbon atoms.
The amount of the diglyceride serving as Component (A) is preferably 30 wt. % or greater, more preferably 40 wt. % or greater in the whole oil/fat contained in the emulsified beverage of the present invention. Within the above-described ranges, taste with less greasiness is available.
From the viewpoint of body fat reducing effects, preferred are Component-(A)-containing oils/fats having 0.1 to 74.9 wt. % of triglycerides, 25 to 95 wt. % of diglycerides and 0.1 to 5 wt. % of monoglycerides are preferred, of which those having 5 to 59.9 wt. % of triglycerides, 25 to 90 wt. % of diglycerides and 0.1 to 5 wt. % of monoglycerides are more preferred, with those having 5 to 49.9 wt. % of triglycerides, 50 to 90 wt. % of diglycerides and 0.1 to 5 wt. % of monoglycerides being especially preferred.
When the emulsified beverage is a processed milk product, the diglyceride content in the oil/fat is preferably reduced to 30 wt. % or less in order to supplement triglycerides as a nutrient.
It is preferred to incorporate, in the packaged emulsified beverage of the invention, Component (A) in an amount of 0.1 to 8 wt. %, more preferably 0.1 to 5 wt. %, especially 0.2 to 5 wt. %, still more preferably 0.2 to 2 wt. %. Within the above-described ranges, the emulsified beverage after retort sterilization or UHT sterilization has high emulsion stability while maintaining good taste. Particularly when it is incorporated in a processed milk product, a weight ratio of Component (A) to milk fat preferably falls within a range of 10:90 to 40:60, more preferably 10:90 to 35:65, especially 10:90 to 30:70. Within the above-described ranges, the resulting beverage becomes smooth to drink and is therefore preferred. When the Component-(A)-containing oil/fat is added to the emulsified beverage, its amount is preferably 0.1 to 10 wt. %, more preferably 0.1 to 8 wt. %, especially 0.1 to 6 wt. % from the viewpoint of emulsion stability.
Examples of the phospholipid serving as Component (B) to be used in the present invention include phosphoric-acid-containing-lipids such as (1) diglyceride-3-phosphoric acid (phosphatidic acid) and derivatives thereof, and monoglyceride-3-phosphoric acid (lysophosphatidic acid) and derivatives thereof, (2) ceramide-1-phosphoric acid (ceramidephosphoric acid) and derivatives thereof, and (3) mixtures containing at least one of the compounds (2) as a constituent.
Specific examples of (1) include phosphatidylcholine, phosphatidylserine, phoaphatidylinositol, phosphatidylethanolamine, phosphatidyl-N-methylethanolamine, and phosphatidyl-N,N-dimethylethanolamine and these components in the lyso form.
Specific examples of (2) include sphingomyelin, ceramide phosphorylethanolamine and ceramide phosphoryl glycerol.
Specific examples of (3) include lecithin and lysolecithin purified from soybean or egg yolk.
The lipoprotein as Component (B) is a complex between a lipid and a protein. As the lipoprotein, a complex between a phospholipid and a protein is more preferred. The lipoprotein is available by mixing a phospholipid such as soybean lecithin or yolk lecithin with a protein such as milk protein or soybean protein and then kneading or lyophilizing the mixture.
As Component (B), lecithin, lysolecithin and lipoprotein are preferred, of which lecithin and lysolecithin are more preferred, with lecithin being especially preferred. A mixture of at least two of them may be used. Alternatively, a food (milk, soybean milk, etc.) containing phospholipid and/or lipoprotein may be used as Component (B).
From the viewpoint of emulsion stability, it is preferred to add Component (B) in an amount of 0.01 to 0.5 wt. %, more preferably 0.02 to 0.4 wt. % in the packaged emulsified beverage of the present invention.
The smaller a ratio of the average particle size, in the oil/fat in the emulsified beverage, after sterilization to that before sterilization [(after sterilization/before sterilization)xc3x97100], the better, because when the ratio is smaller, the taste of the beverage is not impaired even by the long-term storage after sterilization. The ratio of 150 or less, more preferably 130 or less, especially 115 or less is preferred.
The average particle size in the oil/fat in the emulsified beverage is a value measured by laser diffraction, for example, by a particle size distribution analyzer (xe2x80x9cSALD-2100 MD xe2x80x9d, trade name; manufactured by Shimadzu Corporation). The oil/fat in the form of fine particles having an average particle size of 1 xcexcm or less is preferred, because at such a particle size range, the resulting beverage is palatable and smooth to drink.
The packaged emulsified beverage of the present invention preferably contains, in addition to Components (A) and (B), a milk component. Examples of the milk component include milk, sterilized milk, skim milk powder, whole milk powder, concentrated milk, condensed milk, casein, milk whey protein and milk whey mineral.
In the packaged emulsified beverage of the present invention, it is possible to incorporate a sweetener, acidifier, inorganic acid, inorganic acid salt, organic acid and/or organic acid salt as needed. Examples of the sweetener include sucrose, glucose, fructose, isomerized liquid sugar, glycyrrhizin, stevia, aspartame, fructo-oligosaccharide, galacto-oligosaccharide, malt syrup, erythritol, suclarose, maltose, sorbitol and saccharin sodium. An artificial sweetener such as Acesulfame K is also usable. The above-exemplified sweetener is preferably added in an amount of 0 to 60 wt. %, especially 0 to 20 wt. % in the emulsified beverage.
Examples of the acidifier include, as well as juices extracted from natural components, citric acid, tartaric acid, malic acid, lactic acid, fumaric acid and gluconic acid. The acidifier is preferably added in an amount of 0 to 10 wt. %, more preferably 0 to 5 wt. % to the emulsified beverage.
Examples of the inorganic acid or salt thereof include phosphoric acid, sodium phosphate, sodium metaphosphate, sodium polyphosphate arid sodium bicarbonate, while those of the organic acid or salt thereof include citric acid, succinic acid, itaconic acid, malic acid, sodium citrate and gluconic acid. These acids are preferably added in an amount of 0 to 10 wt. %, more preferably 0 to 5 wt. % in the emulsified beverage.
To the above-described components, it is possible to add, as desired, vitamins such as sodium ascorbate, carragenan, dextrin, cyclodextrin, antioxidants, flavors, colorants, preservatives, seasonings, juice extracts, vegetable extracts, nectar extracts, pH regulators and quality stabilizers. Water, carbonated water, coffee bean extract or black tea extract may be incorporated if necessary.
The packaged emulsified beverage of the present invention is preferably an emulsion type beverage such as processed milk product, milk coffee, cocoa, milk shake, milk tea or soup, of which milk tea, milk coffee or processed milk product is preferred.
The pH of the packaged emulsified beverage of the present invention is preferably 3 to 8, more preferably 4 to 7.5, especially 5 to 7 at 25xc2x0C. Such pH ranges are sufficient for preventing aggregation of oil/fat globules, creaming and oil-off.
Examples of the package to be used for the packaged emulsified beverage of the present invention include molded or formed packages composed mainly of polyethylene terephthalate (so-called PET bottle), metal cans, paper packages lined with a metal foil or plastic film, bottles and cups to be hermetically sealed.
The packaged emulsified beverage of the present invention can be prepared, for example, by filling an emulsified beverage in a package such as metal can and then sterilizing the packaged emulsified beverage under conditions as prescribed by Food Sanitation Law. If the package is not suited for retort sterilization, for example, PET bottle, paper pack or hermetically-sealing type plastic cup, employed is a method of sterilizing the package at high temperatures in a short time under sterilizing conditions similar to the above-described ones, for example, by using a plate type heat exchanger, cooling it to a predetermined temperature and then, filling the emulsified beverage therein. Alternatively, it is possible to fill a portion of the components in a package, sterilize the resulting package and then aseptically fill the remaining portion of the components, which has been sterilized separately, in the package.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.